Optical communications systems generally include stations or terminals connected by an optical transmission path. In an undersea optical communication system, for example, shore stations may be separated by distances of 10,000 km or more. The optical transmission path may include an optical fiber cable coupled from one station to another through various elements or components, such as repeaters, branching units, etc. The optical fiber cable may include multiple optical fiber pairs for bi-directional transmission of information, e.g., on a plurality of separate wavelength channels in a wavelength division multiplexed (WDM) system, and a power conductor for providing electrical energy required for operation of the elements connected thereto.
The components in an optical communication system are often located remotely from the stations and in an undersea optical communication system may be located on the ocean floor. These components often are controlled remotely by sending commands from the stations to the remote components. A branching unit, for example, may be controlled remotely to provide optical and/or electrical switching. The station may not know, however, if a command is received and a function is performed in the remote element unless a confirmation is sent back to the station. Although the commands may be sent as optical commands to the remote components over the optical transmission path, providing the confirmation back to the station over the optical transmission path is more challenging. An optical transmitter or regenerator may be provided in the remote components for generating and transmitting an optical command; however, this may add significantly to the cost and may reduce the reliability of the components. In addition to confirming the receipt of a command and/or performance of a function, it may also be desirable to communicate other information (e.g., internal hardware status) from remote components in an optical communication system.